Sound signal



Patented Dec. 25, 1928.

UNITED STATES ROBERT M. GRITCI-IIEIELD, F ANDERSON, INDIANA, ASSIGNOR, BY MESNE ASSIGN-- PATENT OFFICE.

MENTS, 'I'O DELCO-REMY CORPORATION, OF DAYTON, OHIO, A CORPORATION OF DELAWARE.

sounn sIcNAL;

Application filed May 28, 1926. Serial No. 112,269.

. This invention relates to sound signals and particularly to horns for automotive vehicles.

One object of the present invention is to simplify the constructionand to reduce the cost of manufacture of horns of the type in which the diaphragm is vibrated by an electromagnet.

Another object of the present invention is to.improv e the construction of the magnetic circuit of the electromagnetic motor following description, reference being had to the accompanying drawings, wherein a preferred form of embodiment of the present 0 invention is clearly shown.

In the drawings:

Fig. 1 isa rear end view of a horn em bodying the present invention, the cover enclosing the electromagnet being removed.

Figs. 2, 3 and 4 are sectional views taken respectively on the lines 22, 33 and 44 of Fig. 1.

" Referring to the drawings, ldesignates a diaphragm-which is clamped by screws 21 30 and nuts 22 between flanges 23 and 24 of diaphragm housing members 25 and 26 respectively. The member 26 provides a collar for supporting a projector 27.' The housing member 25 may be described as a cup-shaped mem- 5 her having its end wall 28 providedwith an aperture 29.

The member 25 provides a frame for supporting an electromagnet, including a magnet frame 31 and a winding 32, and member 40 25 is made preferably of magnetizable ma.-

' terial so as to provide a part of the magnetic circuit of the electromagnet.

Rivets 30 fasten the ends of the U-shaped' magnet frame 31 to the end wall 28. The I magnet winding 32 is locatedbetween insulating discs 33 and 34 upon a magnetizable core 35. The core 35 is provided with an end portion 36 of smaller diameter which extends through a suitable hole in the yoke of 50 the magnet frame 31 and is riveted over at 37 against the rear face of the magnet frame in order to secure the core and winding 1n posltion. 7

The diaphragm is provided centrally with a hole for receiving a bolt 40 having a circular head 41 and a threaded shankwhich receives a nut 42. The bolt 40passes through a magnetizable disc 43, a sleeve 44, one or more shims 45 a washer 46, the diaphragm 20, a washer 47 a tone modifying disc 48 and a lock washer 49. These parts are clamped between the head 41 of bolt 40 and the nut 42.

. The parts 35, 31, 28, 43, 40 and 41 are magnetizableand therefore provide a magnetic circuit for the flux produced bycurrent flowing through the coil 32.

The circuit breaker for controlling the flow of current to the coil 32 in response to 3 movements of the disc or armature 43 includes contacts 50 and 51. Contact .50 is carried by and is electrically connected with a U-shaped spring conductor or cont-act bracket 52 which is in electrical contact with a terminal clip 53 having an apertured car 54. Thecontact 51 is carried by andis electrical- 1y connected with a bracket 55 having its middle portign 56 offset from its end portions 57; The b cket 55 includes an apertured ear'58. The parts 52, 53 and 55 are secured by rivets 59 to a'bracket 60. The part 55 is insulated from the parts 53 and 52 and all of these parts are insulated. from the bracket 60 by an insulating plate 61 and insulating bushings 63 which surround the rivets 59. The bracket 60 is fastened to the end wall 28 of the housing 25 by rivets 62. The free end 63 of the bracket 60 is provided with a plainhole for receiving a screw- 64, which is threadinto a nut 65. The bracket is bent to provide-a shoulder 66 which engages one of the flat sides of the nut 65 to prevent it-from turning when the screw 64 is turned. 'The screw 64 passes through a hole 67 in the end wall 28 and is provided with a head 68 located rearwardly of said wall 28. The head 68 of the screw 64 is provided with radially extending serrations 69 which cooperate with correspondingly formed serrations 7 0' provided by the end wall 28. The bracket 60 is composed of resilient sheet material and yieldingly maintains the serrations 69 and 70 in engagement to prevent accidental turning of the screw 68. The contact bracket 52 carries adjacent its free end a non-conducting button 71 adapted to be engaged by the armature disc 43. By turning the screw 64, the bracket 60 is moved relative to the wall 28, hence the button 71 is moved relative to the armature 43.- In this manner the instant of contact separation relative to the movement of the armature 43 may be adjusted.

leads 73 of thecoil 32 is connected withthe ear 58 of the bracket 55. The other coil lead 74 is connected with a terminaLbolt 75 which is insulatingly supported by the side wall of.

the diaphragm housing 25. The ear 54 of the terminal clip 53, which is connected with contact 50, is connected by-a wire 7 6 with a terminal bolt 77 which is also insulatingly supported by the housing 25. Sparking of the contacts and 51 is reduced by a condenser 80 having its leads 81 and 82 connected with brackets and 53 respectively. -The condenser 80 is attached to a bracket 83 which is secured by a screw 84 .to the rear surface of the houslng end wall 28.

When current flows through the coil 32 the magnetic circuit will be energized and the armature 43 will be attracted toward the core 35 in order to flex the diaphragm 20 rearwa-rdly as viewed in Fig. 2. During rearward movement of the disc 43 the button 71 will be engaged by it, and the contact 50 will be separated from the contact 51 in order to interrupt the circuit of the coil 32. 'VVhen this interruption occurs the diaphragm 20 will move forwardly due toits own resiliency, and the spring conductor 52 will be released to permit the contact 50 to re-engage the contact 51. These operations will. be repeated as long as the terminals and 77 are connected with a current source.

The electromagnet is enclosed by a cup shaped cover 90 having .its circular edge 91 received by an annular shoulder 92 provided by the housing 25. The cover. 90 is secured in position by a screw 93 passing through'a central hole in the cover 90-and received by v a tapped hole 94 in the core 35.

For the production of the best tone it is essential that the force setting the diaphragm in motion act in a direction substantially parallel to the axis of the diaphragm so that the portion of the diaphragm to which the actuating member is attached will vibrate in a direction which is perpendicular to the plane of the diaphragm. f

Vibration perpendicular to the plane of the diaphragm is substantially always assured as long as the air gapbetween the members 28 and 43 remains uniform at all points. However, if for any reason, one portion of the member 43 is brought into closer relation with the member 28 than other. portions thereof, a reduced air gap obtains, at which area there would be aconcentration 'of niagnetic lines of force. Such-concentration results in a greater pull on one side of the movable member than on the other, which in the present instance, would cause tilting of the armature and its member 43 resulting in what might be termed cocking of the diaphragm,

or more specifically would cause the vibra-- tions of said diaphragm to be out of the per:

pendicular to the plane thereof. Such action tends to move the armature out of proper axial alignment with the core 35 which type of vibration would result in a rough tone.

To eliminate such cocking of the diaphragm when the air gap between members 28 and 43 is not uniform, the adjacent surfaces of the core and armature have been so shaped that the magnetic lines of force, passing between said core member and armature memher, are concentrated substantially within a portion of the air .gap between them. This portion on which the flux is concentrated is preferably coaxial or concentric with the diaphragm, and is provided preferably by pro-- viding at leastone of the members with a convex or protuberant surface. Th1s portion tends to maintain the armature coaxial with the'core and resists the tendency of the armau ture to move out of coaxial relation with ture to remain coaxial with the core increases as the armature approaches the. core and the cooking of the diaphragm will be even less at the end of its movement toward the core,

than at the beginning of its movement.

One advantage of the present invention therefore results from the feature of providing means which will automatically compensate for variations in air gaps of the magnetic circuit, so that extreme care in manufacture 1s not necessary to produce satisfactory operation of the sound signal.

1, Another advantage resulting. from the present construction is that the horn may be inspected while operating, in-order to deter-' mine what adjustments should be made to cause the horn to perform according toa certam standard. The air gaps, particularly the narrower onebetween the parts 35 and 41, are

located so that thin metal plates may be inserted through the notch 72 and between the parts defining the gaps in order to determine,

while the horn is assembled, whether the gaps areof the correct width. The circuit breaker also may be inspected through the notch 72. While the form of embodiment of the present invention as herein disclosed,- consti-.

' tutes a-preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which folow. i

the flat end surface of the core so thatthe What is claimed is as follows:

1. Asoundsignal comprising in combination, a housing; a diaphragm secured to the housing; an electromagnet including a winding and a core attached to the housing;

an armature carried by the diaphragm coaxiallyIwith respect to the core andpresenting an end surface ad acent a surface of the core,

said surfaces being so formed relatively to, each other that the lines of magnetic flux passing between the core and armature are concentrated within a region coaxial with respect to the axes of the diaphragm and core; and'a circuit interrupter for control-. 1mg the electromagne-t.

2. A sound signal comprising in combination, hous ng; a diaphragm secured to the housing; an electromagnetincluding a winding and a core attached to the housing; an armature carried by the diaphragm coaxially with respect to the coreand presenting an end surface adjacent a surface of the core, one ofsaid surfaces being convex s o tha t the lines of magnetic fiux,.p'ass1ng between the lines of magnetic flux, passing between the core and the armature, are concentrated withln a regloncoaxial wlth respect to the point of closest approach ofthe armature and core lying in their mutual'axis; and a circuit interrupter for controlling the electromagnet.-

4. A signal device comprising in combination, a frame including an apertured, magnet'izable plate; an electromagnet frame inounted on said plate; a core supported by said frame and magnetically connected with the plate and having a surface facing the aperture in the plate; awinding about the core; a diaphragm supported by the frame, in spaced relation to the plate; an armature carried by the diaphragm .so. as to be coaxial of the core and so that one surface thereof lies adjacent the surface of the core facing the aperture in the plate, one of said adj acentsurfaces being provided with a protuberant portion adjacent the inner surface, to concentrate the magnetic flu); passing from one tothe other within a region concentric with respect to the mutual axis of the core and armature; and a magnetizablefiange extending from the armature beyond the edge of but in spaced relation. to the aperture in the plate.

v 5. tion, a frame includingan apertured, magnetic plate; an electromagnet frame mounted on said plate; a core supported by said frame and magnetically connected with the plate so that the flat, end surface of the core is held adjacent the aperture in the plate; a winding about the core; a diaphragm supported by the frame, in spaced relation with and parallel to the plate; an armature carried by the diaphragm so as tobe coaxial of the core, said armature having a protuberent surface 4 portion held adjacent to, but in spaced relation with thesurface of the core by the diaphragm, to concentrate the magnetic flux passing from one to the other within a region concentric with respect to their mutual axis; and an annular magnetic flange provided on the armature, said flange being greater in transverse dimension than the aperture in the plate so as to extend beyond the edges of said aperture and overlie an annuing maintained in spaced relation to the plate to provide an air gap between said flange and plate, greater in area than the air gap between the adjacent surfaces of the core ROBERT M. oniionrinnn.

A signal device comprisingin combinalar ring portion of the plate, said flange be- 

